shift interrupt problem?

[rebars1]

1971 merc888 Ford302 V8 carbed. I ran the boat this afternoon on muffs in the driveway as I do about every two to three weeks keep things lubed, etc. It started right up and ran fine. I let it warm up for about 15 minutes, then checked the shifting, forward, then reverse a couple of times with no problems. Then the last time I shifted into forward, it did not quite go all the way in. I shifted to neutral, then reverse, and it stalled. I thought it was because I had shifted too slowly and the shift interrupt switch cut out. I put it back into neutral, but when I turned the key, nothing happened. I heard a very faint click (not solinoid, but circuit breaker?) but no engine turnover. I checked the shifter position and also cycled the shifter into forward, manually checked the prop to lock, then checked reverse for prop lock. I checked the shift interrupt switch position, worked it back and forth and it seemed to center properly. I then tried the key again, heard the faint click then nothing.

Any ideas? Of course, I have a potential buyer comming by on Tuesday to check out the boat....figures!

 

[coastalcruiser]

Re: shift interrupt problem?

HOW TO: How the Shift Interrupt system works


http://forums.iboats.com/showthread.php?p=1930449#post1930449

Quote:
The system is NOT designed to work when putting the drive into gear, or when the boat is out of the water and on muffs.

 

[Fishermark]

Re: shift interrupt problem?

As coastalcruiser points out, it sounds like your problem isn't the shift interrupt switch. Here is a post Don S has made with a check list for starting problems:

Starting problem checklist

 

[rebars1]

Re: shift interrupt problem?

Thank you. I am working my through Dons list, however, when I turn the key, the main circuit breaker cuts out. After awhile it resets itself (no reset button).

When I placed a continuity light across the two screws at the shift interrupt switch it had a dull glow, then got bright when I manually moved the switch activator. I watched the light as I moved the shift lever from nuetral to forward, then back to reverse. It was dull, then flashed bright then back to dull as I went into reverse, but never completely off. I would think it would be normally off, then on when the shift levers moved relative to eachother. Bad switch grounding out? or lower cable out of adjustment? I know the shift interrupt switch is not supposed to do anything when on muffs, but mine often does (momentary engine hesitation when going from forward though neutral into reverse)

 

[rebars1]

Re: shift interrupt problem?

Update: Checking at the slave solinoid per Dons' proceedure.

1.."A" to ground---bright light
2.."A" to "D"-------bright light
3.."C" to ground---with ignition switch on "run"---dull light
4.."C" to ground---with ignition switch to "start"--circuit breaker trips..no light.

Is there supposed to be any light in item 3 (with ignition switch on "run"), or only when it is turned to "start"? Can the solinoid suddenly short out?

The circuit breaker keeps tripping when I turn the key from "run" to "start".

 

[Don S]

Re: shift interrupt problem?

3.."C" to ground---with ignition switch on "run"---dull light
4.."C" to ground---with ignition switch to "start"--circuit breaker trips..no light.

Not the solenoide, you loose power to it.
Loose, corroded, connection somewhere between the ignition switch and the C terminal on the solenoid. Could be anywhere. Neutral safety switch included. engine harness connection. impossible to say for sure.

 

[coastalcruiser]

Re: shift interrupt problem?

had an 888 , change the solenoid and use some clr and a little brass brush to clean all those nasty contacts
To test the shift interupt just move the part the shifter moves, if the engine quits its working, that pesky thing needs to be right on, I got help on that.

 

[rebars1]

Re: shift interrupt problem?

In item 3, should not the test light be off with the ignition in the "run" position and come on only when the key is turned to "start"?

 

[Don S]

Re: shift interrupt problem?

Yea, looks like I read them backwards.
It sounds like a bad ignition switch, remove the start wire from the ign. switch and check for voltage at the start terminal, if there is, replace the switch.

 

[coastalcruiser]

Re: shift interrupt problem?

Hi I just wanted to aplogize, to Rebars1 and Don S, Don I didnt read the post carefully sorry about that.
I had a 888 in my boat and the solenoid needed to be replaced often.
Rebars1, don't forget to tell us how you fixed the issue!

Rob

 

[rebars1]

Re: shift interrupt problem?

Appologize for what? No problems, coastal.

The jury is still out on this one. So far, the ignition switch and neutral safety switch check out OK, at least for the connections under the dash. I replaced the connectors to the ignition switch, though, because they looked pretty shabby, and some of the wire insulation was cracked.

Next is to check the continuity to the other end of the ignition wire at the solinoid.

The solinoid and the shift interrupt switches are still suspect.

 

[rebars1]

Re: shift interrupt problem?

I disconnected the Iginition wire from the solinoid to check continuity and voltage from the iginition switch through the neutral safety switch, and it works fine. Watched it cycle on and off as I moved the shifter in and out of gear with the key in the "start" position.

I thought I might replace the solinoid next. The post positions on mine are oriented sided to side, not up and down as in Dons' drawing. The small posts are marked "S" and "I", but the large posts are not marked. Does it matter which side the cable from the battery attaches to? The other side would attach to the starter. I assume the "I" stands for the Ignition wire. Not sure what the "S" attaches to (starter?). The solinoid is grounded through the attachment plate. Right now the yellow wire (ignition) attaches to the "S" post, which is on the same side as where the battery cable attaches. Just want to make sure that that is the correct wiring pattern.

 

[Don S]

Re: shift interrupt problem?

You have a Ford type starter solenoid, or at least should have.
2 large terminals, and 2 small terminals.
I large terminal goes directly to the battery the other large terminal goes to the starter. Assuming you still have the original type starter without an additional starter solenoid mounted on the starter.
The 2 small terminals are I = tan wire to + terminal on the coil. S stands for START, this should have a yellow wire going to the ignition switch.
Ground is through the mounting bracket. If it's not mounted to a good clean ground, it will not work.

 

[rebars1]

Re: shift interrupt problem?

Thanks for confirming that, Don S, that it how it is currently configured.

 

[rebars1]

Re: shift interrupt problem?

Well, it looks like the starter is shorting out the system. When I disconnected the cable to the starter, solinoid clicked OK and the circuit breaker did not trip. When I reconnected it, the was a short rattle-click at the solinoid then the circuit breaker tripped.

The Merc manual said it could be mechanically jambed. It there a way to check/unjamb it without removing the starter? (tapping on it?) Or should I just pull it and get it checked out?

 

[rebars1]

Re: shift interrupt problem?

Well, I pulled the starter and had it checked- no problems. cleaned all the surfaces and reinstalled it. Still tripped the fuse. Then I rechecked the power to where the battery cable attaches to the solinoid and it was off too. So I checked the cables (again) at the battery. I had cleaned the battery posts and cable end connectors before and although the connectors were OK to the posts, I did not get power through until I jiggled the cables. A-ha! the light lit! So I replaced the red cable, but still the circuit breaker tripped. Did the procedure again and this time it was the black cable. The cables ends are attached to the battery terminals with a bolted clamp. I unclamped the cable, scrubbed and cleaned everything, re-assembled, whaddaya know--it worked!

I guess I had been getting enough voltage to light the test light, but not enough power to crank the engine. Cleaning and reclamping the cable end did the trick.

Well, at least all the connections in the starting circuit are now cleaned and tight.

Thanks again for the help.

 

[coastalcruiser]

Re: shift interrupt problem?

amazing what some clr and a little brass brush can do for all those nasty contacts eh?